1. Field
Embodiments of the present invention relate to an erosion-resistant semiconductor processing component which includes an yttrium metal substrate. A method of fabricating such a component is also described.
2. Background
This section describes background subject matter related to the disclosed embodiments of the present invention. There is no intention, either express or implied, that the background art discussed in this section legally constitutes prior art.
Corrosion (including erosion) resistance is a critical property for apparatus components and liners used in semiconductor processing chambers, where corrosive environments are present. Although corrosive plasmas are present in the majority of semiconductor processing environments, including plasma enhanced chemical vapor deposition (PECVD) and physical vapor deposition (PVD), the most corrosive plasma environments are those used for cleaning of processing apparatus and those used to etch semiconductor substrates. This is especially true where high-energy plasma is present and combined with chemical reactivity to act upon the surface of components present in the environment.
Process chamber liners and component apparatus present within the processing chambers used to fabricate electronic devices and micro-electro-mechanical systems (MEMS) are frequently constructed from aluminum and aluminum alloys. Surfaces of the process chamber and component apparatus (present within the chamber) are frequently anodized to provide a degree of protection from the corrosive environment. However, the integrity of the anodization layer may be deteriorated by impurities in the aluminum or aluminum alloy, so that corrosion begins to occur early, shortening the life span of the protective coating. The plasma resistance properties of aluminum oxide are not positive in comparison with some other ceramic materials. As a result, ceramic coatings of various compositions have been used in place of the aluminum oxide layer mentioned above; and, in some instances, have been used over the surface of the anodized layer to improve the protection of the underlying aluminum-based materials.
Yttrium oxide is a ceramic material which has shown considerable promise in the protection of aluminum and aluminum alloy surfaces which are exposed to halogen-containing plasmas of the kind used in the fabrication of semiconductor devices. An yttrium oxide coating has been used and applied over an anodized surface of a high purity aluminum alloy process chamber surface, or a process component surface, to produce excellent corrosion protection (e.g. U.S. Pat. No. 6,776,873 to Sun et al., mentioned above). The protective coating may be applied using a method such as spray coating, physical vapor deposition (PVD) or chemical vapor deposition (CVD) by way of example.
The substrate base material of the chamber wall or liner, of an apparatus component may be a ceramic material (Al2O3, SiO2, AlN, etc.), may be aluminum, or stainless steel, or may be another metal or metal alloy. Any of these may have a sprayed film over the base material. The film may be made of a compound of a III-B element of the periodic table, such as Y2O3 The film may substantially comprise Al2O3 and Y2O3. A sprayed film of yttrium-aluminum-garnet (YAG) has also been mentioned. Examples of a sprayed film thickness range from 50 μm to 300 μm.
There have been problems with aluminum and aluminum alloys which have been spray coated with an yttrium oxide-comprising film to provide corrosion and erosion resistance. While the yttrium oxide-comprising film surface is more corrosion and erosion resistant than the surface of aluminum, or aluminum alloys, or anodized aluminum, the resistance is significantly less than that of a solid yttrium oxide sintered component. However, the electrical conductivity of a solid, sintered yttrium oxide chamber liner or component may be a disadvantage in instances where a conductivity in the range of aluminum is desired. The mechanical properties of the solid, sintered yttrium oxide are a disadvantage compared with aluminum, which is not so brittle; for example, aluminum offers a better tensile strength, yield strength, and flexural strength.
There is a need in the semiconductor industry for improved materials which provide both a highly corrosion and erosion resistant surface, while providing electrical and mechanical properties which are competitive with aluminum.